The history of guns and projectiles dates back at least several thousand years to the original discovery of gunpowder in China. Gunpowder is essentially a mixture of solid chemicals comprised of an oxidizing agent plus reducing agents capable of being oxidized. If gunpowder is confined in a small space in conjunction with a projectile, i.e. a "bullet", and is then detonated, chemical energy changes the solids to hot gases almost instantaneously, and the chemical energy is converted to kinetic energy, causing the projectile to accelerate.
In yet another version of a gun, the projectile is accelerated by the use of coils situated on a barrel in such a manner that the the coils can be energized in turn to produce an electromagnetic field and thereby accelerate the the projectile.
Electromagnetic and coil guns of prior art designs require gigawatt electric power supplies to operate. The weight and the complexity of these power supplies severely limits the potential use of these guns. It is prohibitive to use these guns for systems which require low weight such as space borne weapons or mobile systems.
The development of electromagnetic guns has also been hindered by the factor of severe rail erosion. It is not clear after many year of development whether such problems can be overcome. The most advanced rails developed to date are limited to a few shots. Yet weapon systems employing electromagnetic and coil guns require that at least a few hundred shots be delivered without barrel replacement to be satisfactory.